1. Field of the Invention
The present invention relates to a multi-directional input apparatus which includes an operating member provided with a shaft portion and which outputs an electric signal in accordance with a tilting direction and a tilting angle of the shaft portion when the shaft portion is tilted. More specifically, the present invention relates to a technique for suppressing rattling of the shaft portion of the operating member which can be tilted in multiple directions.
2. Description of the Related Art
In this type of multi-directional input apparatus, when an operating force is applied such that the shaft portion of the operating member is tilted, positions of a pair of interlocking members driven by the operating member are changed. The changes in the positions of the interlocking members are detected by detectors, such as variable resistors and rotary encoders. In the multi-directional input apparatus, the shaft portion of the operating member extends to the outside through an opening in a housing, and the operating member is engaged with the pair of interlocking members in the housing. The operating member is supported such that the shaft portion thereof can be tilted in multiple directions, and the pair of interlocking members are supported such that axial directions thereof are perpendicular to each other and such that the interlocking members are rotatable. The shaft portion of the operating member extends in a direction away from a tilting center around which the shaft portion is tilted, and a part at which the operating force is applied is generally distant from the tilting center. Therefore, there may be a case where it is necessary to suppress rattling of the shaft portion when the shaft portion is tilted.
Japanese Unexamined Patent Application Publication No. 2002-99337 describes an example of a multi-directional input apparatus having a structure for suppressing rattling of the operating member. In this multi-directional input apparatus, a pair of sliding members, which are upper and lower sliding members, and a compression coil spring are provided on the shaft portion of the operating member. The sliding members are moveable in an axial direction of the shaft portion, and have rubbing surfaces which are in elastic contact with respective receiving surfaces provided on the interlocking members. In this example of the related art, the rubbing surface of the upper sliding member is a curved surface that is convex upward, and the rubbing surface of the lower sliding member is a curved surface that is convex downward. The compression spring is disposed between the pair of sliding members and elastically biases the sliding members such that the sliding members are pressed away from each other. One of the interlocking members driven by the operating member has a concave receiving surface at the bottom, and this receiving surface is in elastic contact with the rubbing surface of the upper sliding member. The other one of the interlocking members driven by the operating member has a concave receiving surface at the top, and this receiving surface is in elastic contact with the rubbing surface of the lower sliding member. Thus, when an operating force is applied and the shaft portion of the operating member is tilted, the sliding members smoothly slide along the respective receiving surfaces of the interlocking members in accordance with the tilting direction. Therefore, rattling of the shaft portion of the operating member can be prevented when the shaft portion is tilted, and the operability is improved.
In the above-described example of the related art, the pair of interlocking members are supported such that the axial directions thereof are perpendicular to each other and such that the interlocking members are rotatable, and electric signals corresponding to the rotation directions and the rotation angles of the interlocking members are output from the respective variable resistors. Therefore, when the shaft portion of the operating member is tilted in an arbitrary direction, the tilting direction and the tilting angle can be detected on the basis of the output values obtained by the variable resistors.
In the example of the related art disclosed in Japanese Unexamined Patent Application Publication No. 2002-99337, the upper and lower sliding members, which are externally fitted to the shaft portion of the operating member, are in elastic contact with different receiving surfaces. Accordingly, it is difficult to set sliding resistances between the sliding members and the respective receiving surfaces equal to each other. Thus, the sliding resistances vary in accordance with the tilting direction of the shaft portion, which degrades the operational feel. In addition, in the example of the related art, the compression spring is disposed between the sliding members and elastically biases the sliding members against the upper and lower interlocking members. Therefore, the process of assembling these movable members is not easy, and it is difficult to reduce the size of the apparatus.